Lethal landscape: Some Florida plants are poisonous

By Terry Brite DelValleFor the Times-Union

Friday

Mar 8, 2019 at 12:01 AMMar 8, 2019 at 6:15 PM

If you have young children and/or pets, you know it’s not uncommon for them to pick up a pretty flower, a leaf, a fruit or a seed and place it in their mouth before you can react. The Extension Office receives multiple calls every year, after the fact, to find out if a particular plant is poisonous. Wouldn’t it be nice to know that information up front so you can fence off or avoid a particular plant to protect children and pets?

Children and puppies are at greater risk because of their smaller body weight, and they are more likely to put something in their mouths. At an early age, children should be taught to avoid putting anything other than food in their mouths. Adults should also be cautious. For example, collecting and eating wild mushrooms, unless you are absolutely sure they are edible, can be very hazardous to your health.

Poisonous plants are those that contain phytotoxins, toxic compounds derived from plants, and they are all around us. The level of phytotoxins varies by plant part and plant age. Some poisonous plants are popular as indoor houseplants, many are used in the landscape, while others thrive in the vegetable garden (especially those in the nightshade family: tomato, eggplant, Irish potato, pepper). Leaves and stems of these vegetables, plus potato tubers that are green, contain a toxin called solanine. Some poisonous plants are categorized as skin irritants while others, if ingested, may cause nausea, diarrhea, liver/kidney failure, hallucinations, paralysis, change in heartbeat or cancer. It’s interesting that some of these are actually used in medicines.

A few examples of poisonous houseplants include heart leaf philodendron, peace lily (Spathiphyllum), arrowhead vine (Syngonium), dumbcane (Dieffenbachia), pothos, English ivy and croton. A few common landscape plants that are poisonous include azaleas, oleanders and cycads. All azalea plant parts, including the pollen and honey, are considered toxic. Oleanders, known for their showy flowers, are frequently planted in landscapes and along highway medians. All parts of the plant are poisonous and one leaf is reported to be sufficient to kill an adult person. Even inhaling the smoke when burning debris or using the wood as skewers in preparing food may be fatal.

Two of the biggest threats to dogs and cats are coontie (Zamia spp.) and sago palms (Cycas revoluta). Both the leaves and seeds are poisonous and can cause liver failure. The seeds have the highest level of toxic materials and ingestion of one to two seeds can kill a treasured pet. Now is the time that many of the bright orange coontie seeds are spilling out of the cone-like structures. If you have these plants in your landscape, simply remove the cones/seeds, which may partially eliminate the problem.

There are also many bulb or bulb-like plants that are poisonous. Examples include the gloriosa lily, agapanthus, amaryllis, zephyr or rain lily, caladium, Asian lily, clivia lily and cyclamen. Gloriosa lily is a fleshy vining plant with beautiful yellow and red flowers found gracing many local arbors or fences. All parts of this plant are poisonous, with the highest concentration of poison in the tuber. Deaths have been reported within 4 hours of ingesting the tuber.

Another one that gardeners seem to enjoy growing is the Angel’s trumpet, Brugmansia spp. It gets large, almost tree-like, and the plant is covered with large trumpet-shaped flowers. The poisonous parts are the flowers, leaves and seeds. Ingesting or smoking these plant parts can cause delirium, seizures and even respiratory failure.

Plants that produce berries are especially enticing to young children. Pokeweed is a common roadside plant that produces purple-black berries in late summer and fall. All parts of this plant are considered poisonous, although some eat the new, tender spring foliage as greens after thoroughly boiling and discarding the first water. Lantana, another popular flowering perennial, can be very attractive to young children when berries form. All parts of this plant are poisonous, especially the leaves and green berries. Additionally, ingesting holly berries can cause nausea and vomiting. Although mistletoe is typically out of reach for pets and children except at Christmas, the berries are very poisonous and have caused deaths.

Larkspur and delphinium are showy cool season annuals whose leaves and seeds contain toxic alkaloids that, if ingested, may affect the nervous system. Another popular annual is foxglove. Leaves and seeds of this plant contain a powerful heart stimulant, digitoxin. Because of its powerful action on the heart muscles, eating it can cause heart failure.

There are also many plants that make some people itch. Azaleas, tomatoes and poinsettias cause rashes with some folks, but the most common skin irritants are poison ivy, poison oak and poison sumac. All three turn a bright red in the fall and produce berries, which is one reason they are so prolific. For help in identifying these plants, go to: https://edis.ifas.ufl.edu/ep220.

To avoid exposure to phytotoxins, identify the plants in your home and landscape and check their status. For assistance in identifying plants, take a cutting to your County Extension Office or to a local nursery. Make sure the cutting is long enough to show the arrangement of the leaves. There are multiple websites that list plants that are toxic to dogs, cats and horses. Once identified, you can remove or block access to those plants. Educate children at an early age not to put things in their mouths. Keep a close eye on puppies, as they love to chew things.

If you suspect your child or pet has eaten a poisonous plant, remove any plant material from their mouth. Rinse their mouth and lips with cool water and then wash your hands with soap and water. Call your physician, veterinarian, or poison control center at 1-800-222-1222. This is a nationwide number. If the person is having seizures, trouble breathing or will not wake up, call 911. Do your homework so you don’t have to deal with regret and remorse. Protect those most dear to you and learn about the plants in your home and landscape.

Terry Brite DelValle is an environmental horticulture program specialist with the Duval County Extension Service and the University of Florida/IFAS.

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